mycnc:mycnc_pulse_width_setup
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mycnc:mycnc_pulse_width_setup [2019/04/17 13:15] – ivan | mycnc:mycnc_pulse_width_setup [2019/04/24 13:32] – ivan | ||
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====Selecting the Appropriate Pulse Width for your motor==== | ====Selecting the Appropriate Pulse Width for your motor==== | ||
- | A common procedure required for proper motor operation is selecting the appropriate pulse width for the signal going from the controller to the step/servo motor on the CNC machine. The pulse impulses sent from the controller to the motor have a certain width (as seen below), that cannot be too large due to the signal overlap that would occur otherwise because of each individual signal interfering with the next one. However, as seen in the following instructions from Panasonic' | ||
- | {{:mycnc:pulse-width: | + | A common procedure required for proper motor operation is selecting the appropriate |
- | {{:mycnc: | + | |
- | As another example, the Yaskawa' | + | {{: |
- | {{: | + | As another example, the Yaskawa' |
- | As such, the pulses have to have both a minimum width, such that the motor (or the particular setting of that motor, as with the Panasonic MINAS A5-series) is able to register pulses that are sent to it, and a maximum | + | {{: |
- | **In order to select | + | A step motor also requires a minimum pulse width, which is considerably higher than that of a servo motor (around ten to twenty times higher higher when comparing the specs for the Leadshine step motor below to the Yaskawa servo drive): |
+ | {{: | ||
+ | |||
+ | As such, the pulse impulses sent from the controller to the motor have to have a certain minimum width for the motor to be able to register those signals. However, that signal width also cannot be too large due to the signal overlap that would otherwise occur due to each individual signal interfering with the next one. This is done by ensuring the controller sends impulse signals at a rate that is lower than the period of the impulse at its maximum frequency, resulting in impulse signals that do not interfere with one another while the width of the signal is wide enough for the motor to register the impulse. | ||
+ | |||
+ | These constraints on the minimum and the maximum pulse width create a permissible range of pulse widths for each motor depending on its hardware specifications and the particular speeds it is required to be operated at. Such an optimal | ||
+ | |||
+ | ====Pulse Width Calculations==== | ||
*Choose the speed at which your machine will move in **[meters / minute]** | *Choose the speed at which your machine will move in **[meters / minute]** | ||
- | *Convert the **[meters / minute]** speed with which the machine | + | *Convert the **[meters / minute]** speed with which the machine |
- | *For example, if the desired **[meters / minute]** speed is equal to 5 meters/ | + | *//For example, if the desired **[meters / minute]** speed of the machine |
+ | < | ||
+ | 5 meters/ | ||
+ | 80 millimeters/ | ||
+ | The value for the [revolutions / second] will be equal to 16 revolutions/ | ||
+ | </ | ||
+ | |||
+ | *Locate the minimum **[seconds / step]** value of your step/servo motor (the minimum time it takes the motor to process each individual impulse). This minimum time should be provided in the motor manual. | ||
+ | | ||
+ | |||
+ | *Using the **[revolutions / second]** value and the minimum allowed **[seconds / step]** value of the motor, calculate how many **[steps / revolution]** the stepper driver will have to make. | ||
+ | | ||
+ | < | ||
+ | 1 ÷ (16 revolutions/ | ||
+ | The value for the number of [steps / revolution] will be equal to 7812.5 steps/ | ||
+ | </ | ||
- | *Locate the minimum **[seconds / step]** value of your step/servo motor (the minimum time it takes the motor to process each individual impulse) | ||
+ | *As discussed earlier, the value selected on the stepper motor must be equal or smaller than the number of **[steps / revolution]** obtained from the previous step for the motor to register the signal and function properly. | ||
+ | *//For example, if the **[steps / revolution]** value has been calculated to be 7812.5 steps/ | ||
- | *Using the **[revolutions / second]** value and the minimum allowed | + | *Using the **[revolutions / second]** value and the updated stepper driver **[steps / revolution]** value, calculate the actual |
- | *For example, if the **[steps / revolution]** value has been calculated | + | |
+ | < | ||
+ | 1 ÷ (16 revolutions/ | ||
+ | The value for the [seconds / step] will be equal to 9.76 μs/step. | ||
+ | </ | ||
- | *Using the **[revolutions / second]** value and the updated stepper driver **[steps / revolution]** value, calculate the actual **[seconds / step]** value of the motor. This value will always be equal or higher than the minimum allowable **[seconds / step]** value of the motor. | ||
- | *For example, if the **[revolutions / second]** value was equal to 16 revolutions/ | ||
*The value for the **Pulse Width** in myCNC software must be equal or higher than the actual **[seconds / step]** value of the motor. | *The value for the **Pulse Width** in myCNC software must be equal or higher than the actual **[seconds / step]** value of the motor. | ||
- | *For example, if the **[seconds / step]** value was equal to 9.8 μs/step, and an ET6 or an ET7 board was used, 12 μs would be selected from the chart in the **Common Hardware Settings** tab as it is the closest value that's higher than 9.8 μs. | + | *//For example, if the **[seconds / step]** value was equal to 9.76 μs/step, and an ET6 or an ET7 board was used, 12 μs would be selected from the chart in the **Common Hardware Settings** tab as it is the closest value that's higher than 9.76 μs// |
{{: | {{: | ||
- | *The 12 μs corresponds to Setting 7 in the chart, thus the **Pulse width** value should be set to 7. | + | *The 12 μs corresponds to Setting 7 in the chart, thus the **Pulse width** value should be set to 7 in myCNC software. |
- | | + | *//NOTE: The first value in the **Pulse Width** line refers to the first four axes of the controller (for example, the horizontal X and Y axes), while the second value refers to the other two axes of the controller (for example, the vertical Z axis). These values are set to be different if the controller used on the vertical axis is separate from that used on the horizontal, and are left the same if a single |
{{: | {{: | ||
- | *The pulse width setup is now complete. | + | *The pulse width setup is now complete. |
mycnc/mycnc_pulse_width_setup.txt · Last modified: 2024/01/22 11:05 by ivan